The Board of Supervisors voted on Tuesday to inventory county buildings and vehicles that could be used for advertising, with an eye toward collecting ad revenues to combat homelessness.

Supervisor Mark Ridley-Thomas, who unsuccessfully backed a quarter-cent sales tax increase for the same purpose, proposed the new revenue source.

Los Angeles County's portfolio of properties includes about 4,000 buildings and nearly 11,000 emergency and non-emergency vehicles, according to the supervisor.

Ridley-Thomas said major buildings next to highways or major traffic thoroughfares could generate significant revenue, noting that public transit systems have accepted ads for years.

"Municipal advertising should follow clear county guidelines on advertising standards that prevents offensive messages and visual clutter," his motion says.

In 2001, the board considered opening up county websites to advertising, but unanimously declared its sites a public asset and barred any links other than for a public, rather than profit, purpose. Potential advertising revenues, if calculated, were not disclosed at the time.

A report on the pros and cons of Ridley-Thomas' proposal, including revenue projections, is expected back in two months.